[colord-kde] Use more appropriate icon, because the activities icon got changed

Summary:
Use a more appopriate icon, because the activities icon got changed in D22155.

Test Plan: Open the Color Corrections KCM.

Reviewers: Plasma, VDG, ndavis

Reviewed By: VDG, ndavis

Subscribers: VDG, Plasma

Differential Revision: https://phabricator.kde.org/D22171